Isn't always on voice search (which is always listening on suitable hardware such as Nexus) and regular search from the Google search bar including results from the supporting apps a universal search?
It'll pop up links to apps if you search for their names, and it can just open them directly if you say something like "open app hacker news." There are also a few that integrate with other magic spells for voice search - mostly it's Google apps, but the Spotify app is registered as a provider of music, so I can say "play Radiohead" and the system will open Spotify and start playing.